The present invention relates to transfer members useful in electrostatographic reproducing apparatus, including digital, image-on-image and contact electrostatic printing apparatus. The present transfer members can be used as transfer members, transfuse or transfix members, transport members, and the like.
In a typical electrostatographic reproducing apparatus such as electrophotographic imaging systems using a photoreceptor, a light image of an original to be copied is recorded in the form of an electrostatic latent image upon a photosensitive member and the latent image is subsequently rendered visible by the application of a developer mixture. Generally, the toner is made up of resin and a suitable colorant, such as a dye or a pigment. Conventional charge director compounds may also be present. The developer material is brought into contact with the electrostatic latent image and the colored toner particles are deposited thereon in image configuration.
The developed toner image recorded on the imaging member is transferred to an image receiving substrate, such as paper, via an transfer member. The toner particles may be transferred by heat and/or pressure to an transfer member, or more commonly, the toner image particles may be electrostatically transferred to the transfer member by means of an electrical potential between the imaging member and the transfer member. After the toner has been transferred to the transfer member, it is then transferred to the image receiving substrate, for example by contacting the substrate with the toner image on the transfer member under heat and/or pressure.
Polymeric transfer members, e.g., transfix/transfuse belts are used in the art. Certain materials such as polyimides are used in transfix belts are preferred because of the high temperature stability, toughness, flexibility and low thermal expansion provided by this material. However, under typical operating conditions in electrophotographic apparatus, slippage exists with current polyimide belts upon thermal cycling. To illustrate, the thermal expansion coefficient of a polyimide belt is enough to expand the belt dimensions from, e.g., a nominal dimension of 97xc3x9730 in2 at ambient temperature to 97.1xc3x9730.1 in2 at a typical operating temperature of 120xc2x0 C. To compensate for this problem, the belt is typically placed under higher tension, leading to a life shortfall and machine downtime due to maintenance calls.
The present invention relates to transfer members for electrophotography which are more durable and have longer life, and are also easier to fabricate compared to those which have come before it.
Transfer members of the invention feature a substrate comprising a nanosize polymer material. The nanosize polymer material may be a particulate organically modified mica, e.g., muscovite, lepidolite, phlogopite or glauconite; a particulate organosilicate clay filler material such as organically modified talc-type silica (OMTS) in nanosize particulate form, or organically modified bentonite, e.g., montmorillonite; allophane; kaolinite; halloysite; illite; chlorite; vermiculite; sepiolite; attapulgite; palygorskite; and mixed-layer clay minerals in nanosize particulate form. The substrate may be a thermosetting or a thermoplastic resin e.g., epoxy resins (diglycidyl ether of bisphenol A); polyethyleneterephthalate (PET), polyvinylfluoride, urethane rubber, polytetrafluoroethylene, or a polyimide. The substrate preferably includes a polyimide material. The amount of nanosize polymer material in the substrate is generally lower than about 10% by weight, advantageously between about 10% and 5% by weight, and more advantageously at least about 5% by weight.
The invention further relates to apparatus for forming images on a recording medium. Such image forming apparatus include a charge-retentive surface to receive an electrostatic latent image; a development component to apply a developer material to the charge-retentive surface to form a developed image on the charge retentive surface; and a transfer component to transfer the developed image from the charge retentive surface to a copy substrate. The apparatus may also include a fixing component to fuse the transferred developed image to the copy substrate. The fixing component may be separate from the transfer component, or one element may serve both functions. The transfer member preferably includes a substrate containing a filler material adapted for reducing the thermal expansion coefficient of the transfer component.